The invention relates to a stop member having a panel thinness measuring device for use with a positioning conveyor for horizontally aligning panels, sheet metal and the like with a conveying table, provided with a driving means, and the stop member being at an edge of the conveying table.
With machining panel materials of all types, especially sheet metal or blanks, billets or bars, in one machining station, especially with metal-forming machine tools, it is necessary to position the individual pieces precisely in the horizontal direction before the machining. In this sense, the object of the invention is referred to as xe2x80x9cpositioning conveyorxe2x80x9d since it has, at least, the function of conveying and positioning the conveyed panels. In practice, usually individual panels are taken from a stack, transferred to the positioning conveyor addressed here, moved on this against a stop and also accurately positioned laterally and then inserted, perhaps with a suction cup lifting conveyor, precisely in position in the machining station. The positioning conveyor therefore represents the last station before the machining device. Here there is also the last opportunity to check whether the singling has actually taken place.
Particularly in case of thin panels, it may happen that two or more panels pass through the singling equipment, if the panels are glued together by rust preventatives, drawing agents, etc. or connected by adhesion. However, if two or even three panels are brought into the downstream machining station, loads arise, for which this station is not equipped so that, as a rule, the tools or even the machining station as a whole, are damaged or even destroyed. Similar problems arise if a panel of greater thickness happens to be among the panels supplied. It is consequently of a great importance that only an intended panel reaches the machining station.
It is therefore an object of the invention to provide a positioning conveyor of the type named above, by means of which the aligned panels can be checked in relation to the effective singling of the panels.
Pursuant to the invention, this objective is accomplished for a positioning conveyor of the above type by a thickness-measuring device, which is provided at the stop for measuring the panel thickness of the contacting panels, sheet metal or the like.
If the nominal thickness of the panel has been entered into such a measuring device at the start, such a thickness measurement itself, even if the accuracy of the measurement is limited, can determine whether only one panel or two or even more panels have reached the aligned position. If more than one panel is measured, an appropriate signal from the measuring device can then stop the equipment.
Preferably, an anvil surface, which supports the contacting panels, is provided at the stop and at least one tracing finger, which can be lowered, is mounted at the stop in a position above the anvil surface. The contacting panels can therefore be clamped with an appropriate force between the anvil surface and the tracing finger. By these means, measuring errors, which arise because of a curvature of the measured panels, are avoided.
Preferably, the tracing finger is mounted pivotably at the stop. This is a solution, which not only can be realized easily constructively, but also one which offers the advantage that the tracing finger can be swiveled out of the region above the panel and the panel can be lifted off with a lifting conveyor or a robot arm. The swiveling movement can be detected by a distance measuring device, which produces a distance signal, either directly or after conversion into a linear movement. The distance-measuring device preferably is constructed so that it puts out the difference between a measurement signal when the tracing finger is lowered completely onto the anvil surface and when it is lowered onto the surface of a contacting panel, as a signal reflecting the thickness of the panel.
The swiveling of the tracing the finger can be converted, for example, by a rack-and-pinion gear into a linear motion of the armature of a differential transformer.
In the case of a preferred embodiment, two tracing fingers at the stop, mounted pivotably on a common axis, are laterally offset so that panels, which come in at an angle and the leading edge of which is not at like angles and perpendicular to the conveying direction, can also be detected.